Forests constitute the largest renewable resource on which hings the sustenance of general economy of many a developing nations like India. They are, however, very sensitive to maltreatment and unless properly managed and Judiously utilized and are prone to deteriorate in many a ways to the extent of vanishing. The ever-escalating population vis-à-vis rising living standard, rapid industrialization and urbanization have brought about heavy onslaught on forests leading to fast depletion and degradation. Many of the areas once under luxuriant forest cover have practically denuded and decimated or almost become extinct.It is, therefore, pertinent that a carefully thought-out strategy is the need of the day to be adapted for the balanced and judious utilization of the most precious resources which the nature has bestowed us so much so that we can preserve and conserve maximum and deteriorate the least. It is in this context that a need has been felt for the inventorization of natural resources which broadly means periodic assessment of forest resources as well as the land on which these subsist ad sustain with regard to various parameters and this assumes greater contemporary relevance in our country. Forest inventory provides necessary data base for long term strategy on long term basis. Unfortunately, in absence of a sound and adequate database, major constraint in forestry planning has become a big bottleneck. In other words, this has hurdled in proper planning and orientation of the forest resources in a bigger way. To fill this void, a specialized organization nomenclaturized as pre-investment survey of forest resources (PIS) was created far back in the year 1965 under a Joint project of FAO, UNDP and GOI which lasted till 1968. Thereafter, the work continued independently under Indian expertise. The primary responsibility of the PIS was to investigate and report on the prospects of economic availability of forest run material to feed industrial projects in selected areas of the country.A secondary and long term responsibility of establishing a nucleus of Natural forest resources, survey providing continuous and relievable information about the forest resources of the country was also assigned to it. Though, PIS fared in achieving the short term objectives, the fulfillment of long term objectives eluded it. The National commission on Agriculture was prompt enough to take cognizance of this short coming and put forward a number of proposals of far reaching importance in its interm report in 1974 and the final report of 1976, stressing mainly the necessity of integrated long term planning in forestry sector and creation of Natural forest resources, survey organization with broad based objectives to play a pivotal role in the planning process. The PIS was thus converted into Forest Survey of India with effect from June1, 1981.The inventory carried out by FSI was a National Forest Inventory of the country's forest resources. An inventory of this type was carried out on repetitive basis and took strategic decision. A systematic cluster compelling design at grid intervals was as well adopted for the proposed National forest inventory. Application of aerial photo interpretation in forest inventory was introduced in our country in 1965 by the erstwhile PISFR for preparation of forest types and thematic maps and since then this has expanded considerably.Aerial photographs and ground maps are procured from survey of India and the interpretation keys and methodologies are standardization and interpretations from Aerial photos are carried out to produce the forest types thematic maps with the help of survey of India. A certain amount of field checking is also done in the process. The most useful product for vegetation mapping is the false colour composite. The forest survey of India has completed a project on preparation of the National vegetation map of India. More sophisticated systems with higher resolutions are available for forest resource appraisal.